Electrical connectors – Contact comprising cutter – Insulation cutter
Reexamination Certificate
1995-12-20
2001-09-18
Paumen, Gary F. (Department: 2833)
Electrical connectors
Contact comprising cutter
Insulation cutter
C439S395000
Reexamination Certificate
active
06290531
ABSTRACT:
This Application claims the priority of Japanese Application 6-335729, filed Dec. 20, 1994.
The present Invention is an improvement on single-core or multi-core electric cables for use with a cramping terminal which includes a conductive wire which is to be pressed into a slit formed therein. The present Invention also relates to an electric connector comprising one or more of the foregoing cables.
BACKGROUND OF THE INVENTION
A known cable of this type is shown in
FIGS. 7 and 8
. It consists essentially of conductive wire
1
having a circular cross section and insulating sheath
2
covering wire
1
. When this cable is pressed into slit
3
a
in cramping terminal
3
, edges of slit
3
a
penetrate insulating sheath
2
and linearly cut into the outer portion of conductive wire
1
, thereby making electrical contact therewith.
In such a structure, if the contact area between wire
1
and slit
3
a
is smaller than the cross section of wire
1
, the electrical resistance of the contact portion is larger than that of wire
1
. This is not desirable because it causes local generation of heat. Considering the thickness of the plate forming cramping terminal
3
, the diameter of conductive wire
1
, the rate of deformation of the conductive wire as it is pressed into the slit, as well as other factors, width W of slit
3
a
of terminal
3
is such that the contact area between conductive wire
1
and cramping terminal
3
is larger than the cross section of conductive wire
1
. To accomplish this, width W must be considerably smaller than the diameter of conductive wire
1
. Particularly, when a thick conductive wire
1
is used, the lateral edges of slit
3
a
cut more deeply into the outer portion of conductive wire
1
. Thus, a greater pressing force is required, making the cable pressing operation more difficult.
Comparing an electrical wiring using the cables and the cramping terminals of this type with a busbar type wiring using conductive plates as conductors, the temperature of the conductors increases to a greater extent in the former wiring, thereby necessitating measures to cope therewith. The temperature increase is greater in the former case because the surface area of the conductive wire having a circular cross section is smaller than that of the busbar having a rectangular cross section, provided, of course, that both cross sections have the same total area.
SUMMARY OF THE INVENTION
In view of the above problem, it is the object of the Invention to provide an electric cable for use with a cramping terminal and an electrical connection means comprising the above electric cable with an improved operability and in which the temperature increase of the conductive wire is minimized.
According to the Invention, the cable for use with the cramping terminal includes a conductive wire which has a polygonal cross section, preferably having at least four sides. If the conductive wire is polygonal in cross section with an even number of sides, two opposing sides are parallel to each other. In this case, the cable is pressed into the slit of the cramping terminal with the two opposing sides in contact with the corresponding lateral edges of the slit. This minimizes the portion of the conductive portions to be cut by the sides of the slit, thereby making the force required to press the cable into the slit of the cramping terminal smaller. Further, since the two opposite sides contact the entire lateral edges of the slit, the density of the current flowing through the contact portions becomes smaller, thereby minimizing local generation of heat. When the conductive wire has a polygonal cross section having an odd number of sides, the two opposing sides are not parallel. However, the outer portion of the conductive wire to be cut by the slit is still less than with a conductive wire having a circular cross section.
Thus, because the outer portion of the conductive wire which is to be cut by the slit is reduced, less force is required to press the cable into the slit and thereby complete the connection. Moreover, since the opposing sides of the wire contact the sides of the slit along their entire length, the contact area is larger than with the usual circular cross section wires. Therefore, the amount of heat generated per unit area is correspondingly reduced, thereby controlling the local heat generated. Furthermore, if there are two wires having the same cross sectional area, the one with a polygonal cross section will have a larger surface than one with a circular cross section. As a result, the polygonal wires of the present Invention are able to radiate more heat than the circular wires. As a result of all three of the foregoing factors, assembly of the connector is facilitated and the heat problem is minimized.
According to preferred embodiments of the Invention, the polygonal cross section has four or more sides, and is preferably rectangular, pentagonal, or hexagonal. It is also preferred that the polygonal cross section having an even number of sides be equilateral, and the polygonal cross section having an odd number of sides be non-equilateral. The polygonal cross section having an odd number of sides advantageously has two approximately parallel sides which are longer than the other sides.
According to a further embodiment of the Invention, the electric cable also comprises at least two conductive wires, wherein the insulation sheaths of adjacent electric wires are formed integrally, and the conductive wire desirably comprises a plurality of twisted and/or compressed strands. Furthermore, the insulating sheath preferably has a polygonal outer shape, in particular one corresponding to the polygonal cross section of the conductive wire.
According to the Invention, there is also provided an electric connector comprising at least one electric cable according to the Invention and at least one cramping terminal, wherein the conductive wire is pressed into a slit formed in the terminal. According to a preferred embodiment of the Invention, the electric connector comprises at least two electric cables and a cramping terminal bus having at least two cramping terminals, wherein each conductive wire is insertable into a slit formed in a corresponding cramping terminal. Preferably, the slit of each cramping terminal has a width equal to or slightly smaller—preferably by about several tenths of a millimeter—than the width of the conductive wire.
REFERENCES:
patent: 3383456 (1968-05-01), Kosak
patent: 3621118 (1971-11-01), Bunish et al.
patent: 3816818 (1974-06-01), Meier
patent: 3994554 (1976-11-01), Navarro
patent: 4673904 (1987-06-01), Landis
patent: 4692566 (1987-09-01), Kauffman
patent: 5304741 (1994-04-01), Proulx
patent: 5399098 (1995-03-01), Marshall et al.
patent: 9102716 (1991-03-01), None
patent: 2095481 (1982-09-01), None
Inoue Nori
Kobayashi Makoto
Oka Yoshito
Onizuka Takahiro
Saka Yuuki
Bierman, Muserlian and Lucas
Paumen Gary F.
Sumitomo Wiring Systems Ltd.
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